Comparative Effectiveness of Linezolid and Vancomycin Among a National Veterans Affairs Cohort with Methicillin-Resistant Staphylococcus aureus Pneumonia

Study Objective: As variability in vancomycin dosing, susceptibility, and tolerability has driven the need to compare newer agents with vancomycin in real-world clinical settings, we sought to quantify the effectiveness of linezolid compared with vancomycin on clinical outcomes for the treatment of methicillin-resistant Staphylococcus aureus (MRSA) pneumonia. Design: Retrospective cohort study. Data Source: Veterans Health Administration national databases. Patients: Adults admitted to Veterans Affairs hospitals between January 2002 and September 2010 with diagnosis codes for MRSA and pneumonia, and who initiated and received at least 3 days of continuous intravenous vancomycin therapy (4943 patients) or intravenous or oral linezolid therapy (328 patients) while in the hospital. Measurements and Main Results: Propensity score–adjusted Cox proportional hazards regression models quantified the effect of linezolid compared with vancomycin on time to 30-day mortality (primary outcome), therapy change, hospital discharge, discharge from intensive care, intubation, 30-day readmission, and 30-day MRSA reinfection. In addition, a composite outcome of clinical success was defined as discharge from the hospital or intensive care unit by day 14 after treatment initiation, in the absence of death, therapy change, or intubation by day 14. Subgroup analyses were performed in a validated microbiology-confirmed MRSA subgroup and clinical subgroup meeting clinical criteria for infection. Although a number of baseline variables differed significantly between the vancomycin and linezolid treatment groups, balance was achieved within propensity score quintiles. A significantly lower rate of therapy change was observed in the linezolid group (adjusted hazard ratio [HR] 0.68, 95% confidence interval [CI] 0.48–0.96). The clinical success rate was significantly higher among patients treated with linezolid (adjusted HR 1.25, 95% CI 1.07–1.47). Comparable findings were observed in the subgroup analyses. Conclusion: Individual clinical outcomes were similar among patients treated for MRSA pneumonia with linezolid compared with vancomycin. A significantly higher rate of the composite outcome of clinical success was observed, however, among patients treated with linezolid compared with vancomycin

Predictors of Clinical Success Among a National Veterans Affairs Cohort With Methicillin-Resistant Staphylococcus aureus Pneumonia

Background: The treatment of methicillin-resistant Staphylococcus aureus (MRSA) pneumonia is exceedingly complicated, which is concerning because of the high mortality rate associated with the infection. Identification of independent predictors of clinical success can optimize patient care by assisting clinicians in treatment decisions. Objectives: We sought to identify independent predictors of clinical success in a national Veterans Affairs (VA) cohort of MRSA pneumonia patients. Methods: A nested case-control study was conducted among a cohort of VA patients with MRSA pneumonia receiving linezolid or vancomycin between January 2002 and September 2010. Cases included those demonstrating clinical success, defined as discharge from the hospital or intensive care unit (ICU) by day 14 after treatment initiation, in the absence of death, therapy change, or intubation by day 14. Controls represented non-success, defined as therapy change, intubation, ICU admission, re-admission, or death between treatment initiation and day 14. The potential predictors assessed included treatment, patient demographics and admission characteristics, previous healthcare and medication exposures, comorbidities, and medical history. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated from logistic regression. Results: Our study included 2442 cases of clinical success and 1290 controls. Demographics varied between the clinical success and non-success groups, including age, race, and region of facility. A current diagnosis of chronic respiratory disease (46% vs 42%) and diagnosis of pneumonia in the year prior to the MRSA pneumonia admission (37% vs 32%) were both more common in the clinical success group. Despite these significant differences, only two predictors of clinical success were identified in our study: previous complication of an implant or graft, including mechanical complications and infections, in the year prior to the MRSA pneumonia admission (OR, 1.55; 95% CI, 1.17–2.06) and treatment with linezolid (1.53; 1.12–2.10). Predictors of non-success included concomitant urinary tract infection diagnosis (OR, 0.82; 95% CI, 0.70–0.96), intravenous line (0.76; 0.66–0.89), previous coagulopathy (0.74; 0.56–0.96), previous amputation procedure (0.72; 0.53–0.98), current coagulopathy diagnosis (0.71; 0.53–0.96), dialysis (0.54; 0.38–0.76), multiple inpatient procedures (0.53; 0.45–0.62), inpatient surgery (0.48; 0.41–0.57), and previous endocarditis (0.24; 0.07–0.81). Discussion: MRSA pneumonia tends to affect complex patients, and identification of the predictors of clinical success is useful when considering different therapeutic approaches. Conclusions: In a national cohort of VA patients with MRSA pneumonia, treatment was the only modifiable variable predicting clinical success

673. Study of Prescribing patterns and Effectiveness of Ceftolozane/Tazobactam Real-world Analysis (SPECTRA): Results from a multi-national, multicenter observational study

Abstract Background Ceftolozane/tazobactam (C/T) has demonstrated efficacy to treat complicated intra-abdominal infections (cIAI), complicated urinary tract infections (cUTI) and hospital acquired bacterial and ventilator-associated bacterial pneumonia. However, physicians, providers, and other stakeholders including payers want broader real-world evidence to inform clinical decisions and optimize healthcare resource use. Methods SPECTRA is a multi-national, multicenter, retrospective, inpatient, observational study of patients treated with C/T in Australia, Austria, Germany, Italy, Mexico, Spain and The United Kingdom. Adult inpatients treated with ≥48 hours of C/T were included. Demographics, clinical characteristics, treatment management patterns, and outcomes were analyzed. Results There were 687 patients from 38 participating hospitals in 7 countries. The average age was 57.6 years (±17.3 [SD]) and most were male 456 (66.4%). The majority had at least one comorbidity 563 (82.0%), with the most common being heart disease 208 (30.3%), immunocompromised state 207 (30.1%) and chronic pulmonary disease 195 (28.4%). The most common indications were pneumonia 204 (29.7%), sepsis 147 (21.4%), and cIAI 106 (15.4%); 162 (23.6%) had multiple sites of infection and 245 (35.7%) were polymicrobial infections. Median C/T treatment was 12.0 days (11.0 [IQR]). Half of the patients were admitted to the ICU 343 (49.9%), 43.4% of which was related to the infection. Clinical success was 66.1%. All-cause in-hospital mortality was 22.0% with 8.7% being infection related. 30-day all-cause readmission was 9.8% and 4.7% were infection related. Conclusion C/T was used to treat infections among critically ill patients and for multi-source, polymicrobial infections. Despite the complexity of the patients in this real-world analysis, most C/T patients had beneficial outcomes that are similar to results of controlled clinical trials. Disclosures Alex Soriano, MD, MSD, Pfizer, Shionogi, Angelini, Menarini, Gilead: Honoraria Laura A. Puzniak, MPH, PhD, Merck & Co., Inc.: former employee and stockholder David Paterson, MBBS, Accelerate: Honoraria|bioMerieux: Honoraria|Entasis: Advisor/Consultant|Janssen-Cilag: Grant/Research Support|MSD: Advisor/Consultant|MSD: Grant/Research Support|MSD: Honoraria|Pfizer: Grant/Research Support|Pfizer: Honoraria|PPD: Grant/Research Support|Shionogi: Grant/Research Support|VenatoRx: Advisor/Consultant Stefan Kluge, MD, Astrazeneca: Lecture fees|Biotest: Lecture fees|Cytosorbents: Grant/Research Support|Cytosorbents: Lecture fees|Daiichi Sankyo: Grant/Research Support|Daiichi Sankyo: Lecture fees|Fresenius Medical Care: Advisor/Consultant|Fresenius Medical Care: Lecture fees|Gilead: Advisor/Consultant|Gilead: Lecture fees|Mitsubishi Tanabe Pharma: Lecture fees|MSD: Advisor/Consultant|MSD: Lecture fees|Pfizer: Advisor/Consultant|Pfizer: Lecture fees|Phillips: Lecture fees|Zoll: Lecture fees Alexandre H. Watanabe, PharmD, Merck & Co., Inc.: Employee Engels N. Obi, PhD, Merck & Co., Inc.: Employee|Merck & Co., Inc.: Stocks/Bonds Sunny Kaul, BSc, MBChB, PHD, FRCP, FFICM, Chiesi: Speaker fees|Gilead: Speaker fees|GlaxoSmithKline: Speaker fees|MSD: Grant/Research Support|MSD: Speaker fees|Shionogi: Speaker fees|Vifor Pharma: Grant/Research Support

The Comparative Effectiveness of Ceftolozane/Tazobactam versus Aminoglycoside- or Polymyxin-Based Regimens in Multi-Drug-Resistant Pseudomonas aeruginosa Infections

Pseudomonas aeruginosa infections are challenging to treat due to multi-drug resistance (MDR) and the complexity of the patients affected by these serious infections. As new antibiotic therapies come on the market, limited data exist about the effectiveness of such treatments in clinical practice. In this comparative effectiveness study of ceftolozane/tazobactam versus aminoglycoside- or polymyxin-based therapies among hospitalized patients with positive MDR P. aeruginosa cultures, we identified 57 patients treated with ceftolozane/tazobactam compared with 155 patients treated with aminoglycoside- or polymyxin-based regimens. Patients treated with ceftolozane/tazobactam were younger (mean age 67.5 vs. 71.1, p = 0.03) and had a higher comorbidity burden prior to hospitalization (median Charlson 5 vs. 3, p = 0.01) as well as higher rates of spinal cord injury (38.6% vs. 21.9%, p = 0.02) and P. aeruginosa-positive bone/joint cultures (12.3% vs. 0.7%, p \u3c 0.0001). Inpatient mortality was significantly lower in the ceftolozane/tazobactam group compared with aminoglycosides or polymyxins (15.8% vs. 27.7%, adjusted odds ratio 0.39, 95% confidence interval 0.16–0.93). There were no significant differences observed for the other outcomes assessed. In hospitalized patients with MDR P. aeruginosa, inpatient mortality was 61% lower among patients treated with ceftolozane/tazobactam compared to those treated with aminoglycoside- or polymyxin-based regimens